Preheat the oven to 180°C/160°C fan oven/gas 4. Grease and line 2 x 20cm (8in) round cake tins.
Put the butter, oil and sugar in a mixing bowl and beat with a wooden spoon or electric mixer until pale in colour and fluffy in texture.
Add the eggs one a time beating well and scraping down the sides of the bowl after each addition. Then add the Vanilla Extract and Cocoa Powder and mix well.
Add the Red Gel Food Colour and mix until the colour is even and well incorporated.
Sift the flour into a bowl, then add half to the cake mixture along with half the buttermilk and a pinch of salt. Mix together until smooth and then add the remaining flour and buttermilk and mix again.
In a bowl mix together the Bicarbonate of Soda and vinegar then add to the cake mixture stirring it in by hand until it is all incorporated.
Divide the mixture evenly between the two cake tins then bake in the oven for 35-40 minutes until an inserted skewer comes out clean. Allow the cakes to cool in the tins for 15 minutes then remove from the tins and place on a cooling rack to cool completely.
For the buttercream, pop the butter and icing sugar into a large bowl and beat together using an electric hand whisk or freestanding mixer with the beater attachment, until smooth and combined – make sure there are no lumps of butter. Pop in the Vanilla Extract and cream cheese and beat together until you have a lovely light and fluffy buttercream.
Once cooled, place one layer of the cake onto a cake plate and cut the domed top off the cake to make a flat surface. Reserve the cake off-cuts for decorating.
Spread a layer of Icing on top of the cake then place the second layer of cake on top and cover the whole cake in the remaining Icing.
Take your reserved cake off-cuts and crumble into a bowl so that you make fine crumbs.
Sprinkle the cake crumbs around the top edge of the cake to decorate.